Shield assembly for a power tool

ABSTRACT

The present invention is directed toward a shield assembly for a handheld tool device such as an angle grinder. The shield assembly is selectively repositionable with respect to the cutting tool. A lock mechanism secures the shield assembly in discrete rotational positions relative to the cutting tool. The shield assembly includes a guard member and a bumper member, and an alignment feature configured to align the relative positions of guard member and the bumper member, thereby positing the members in a predetermined relative orientation. With this configuration, the shield assembly is selectively repositionable via a “hands-free” mechanism that permits a user to adjust the position of the shield assembly by simply contacting the shield assembly against a work surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 61/503,115, filed on 30 Jun. 2011 and entitled “Accessible GuardLock,” the disclosure of which is hereby incorporated by reference inits entirety.

FIELD OF THE INVENTION

The present application is directed toward a shield assembly for a powertool and, in particular, a shield assembly for an angle grinder that isselectively repositionable with respect to the grinding tool.

BACKGROUND OF THE INVENTION

Powered hand tool devices such as angle grinders typically include aprotective shield to prevent sparks or particulate material from beingdirected toward the operator, as well as to prevent inadvertent operatorcontact with the working tool (e.g., the cutting/grinding blade).Conventional protective guards are solid covers configured to cover aportion of the tool (e.g., a grinding wheel) without interfering withits operation. These guards are rotationally fixed, i.e., they remain ata fixed position with respect to the working tool. Such guards limit theapproach angle of the tool, thereby obstructing the operator'sline-of-sight or forcing the operator to position her body across thetool (e.g., the grinding wheel). Other guards, while repositionable,require the use of a tool (wrench, screwdriver, etc.) to loosenfasteners that secure the guard in position. Moreover, the positionsprovided by such guards are limited, making it difficult for theoperator to properly control debris/sparks under every workingcondition. Consequently, operators often remove these conventionalguards or leave the guard positioned at a convenient, but other thanrecommended angle, increasing the likelihood of injury.

It would be desirable to provide a shield assembly for a power tooldevice that is selectively repositionable in various rotationalpositions with respect to the working tool. It would further bedesirable to provide a guard that is releasable via simple contact ofthe guard against the work surface (e.g., hands free repositioning),thereby avoiding the need for wrenches, screwdrivers, etc. It would alsobe desirable to provide a guard that enables an operator to view theworking tool during operation.

SUMMARY OF THE INVENTION

The present invention is directed toward a shield assembly for ahandheld tool device including a dynamic working tool such as a grindingdisc. The shield assembly, which is repositionable with respect to theworking tool, includes a guard member, a coupling member, and anactuator. A lock mechanism secures the shield assembly in selectedrotational positions relative to the working tool. In operation,engaging the actuator against the work surface releases the lockmechanism, permitting an operator to reposition the shield assembly withrespect to the working tool. The shield assembly may further include analignment feature operable to align the relative positions of theactuator and the coupling member, thereby positioning the components ina predetermined relative orientation. With this configuration, theshield assembly is selectively repositionable via a “hands-free”mechanism that permits a user to adjust the position of the shieldassembly by simply contacting the shield assembly against a worksurface.

The shield assembly may further be adapted to enable the operator toview the working tool through the guard member during operation. In anembodiment, the guard member is provided with a series of apertures thatenable viewing the working tool through the guard member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side perspective view of a handheld power toolincluding a shield assembly in accordance with an embodiment of theinvention.

FIG. 2A illustrates a perspective view of a gear case of the power toolshown in FIG. 1, with the shield assembly removed for clarity.

FIG. 2B illustrates a bottom plan view of the gear case cover shown inFIG. 2A.

FIG. 3A illustrates a front perspective view of a pawl device inaccordance with an embodiment of the invention.

FIG. 4 illustrates an exploded view of the shield assembly and gear caseshown in FIG. 1.

FIG. 5A illustrates a top perspective view of a guard member inaccordance with an embodiment of the invention.

FIG. 5B illustrates a bottom perspective view of the guard member shownin FIG. 5A.

FIG. 6A illustrates a top perspective view of an actuator in accordancewith an embodiment of the invention.

FIG. 6B illustrates a top view in plan of the actuator shown in FIG. 6A.

FIG. 6C illustrates a bottom perspective view of the actuator shown inFIG. 6A.

FIG. 6D illustrates a close-up view of the collar portion of theactuator shown in FIG. 6A.

FIG. 7A illustrates a top perspective view of a coupling member inaccordance with an embodiment of the invention.

FIG. 7B illustrates a top plan view of the coupling member shown in FIG.7A.

FIGS. 8A and 8B illustrate a schematic of an alignment system inaccordance with an embodiment of the invention.

FIG. 9A illustrates a schematic of an alignment system in accordancewith an embodiment of the invention.

FIG. 9B illustrates a schematic of an alignment system in accordancewith an embodiment of the invention.

FIG. 9C illustrates a schematic of an alignment system in accordancewith an embodiment of the invention.

FIGS. 10A-10E illustrate perspective and cross-sectional views of theshield assembly shown in FIG. 1, showing the operation of the shieldassembly.

FIGS. 11A-11D illustrate views of a repositionable shield assembly inaccordance with another embodiment of the invention.

FIGS. 12A-12C illustrate views of a repositionable shield assembly inaccordance with another embodiment of the invention.

FIGS. 13A-13D illustrate views of a repositionable shield assembly inaccordance with another embodiment of the invention.

FIG. 14 illustrates a view of a repositionable shield assembly inaccordance with another embodiment of the invention.

FIGS. 15A and 15B illustrate a see-through guard member in accordancewith an embodiment of the invention.

FIGS. 16A and 16B illustrate a see-through guard member in accordancewith another embodiment of the invention.

FIGS. 17A and 17B illustrate a see-through guard member in accordancewith another embodiment of the invention.

Like reference numerals have been used to identify like elementsthroughout this disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a handheld tool device including a shield assembly inaccordance with an embodiment of the invention. In an embodiment, thehandheld tool device is a powered device with a dynamic working tool,e.g., an angle grinder including a grinding disc. As shown, the handheldtool device 10 includes a housing 105 with a forward gear case 110, afield case 115 housing a motor or armature assembly oriented rearward ofthe gear case, and a handle assembly 120 oriented rearward of the fieldcase. A shield or hood assembly 125, coupled to the gear case 110 of thedevice 10, is configured to shield the operator from debris(sparks/particles) generated during device operation.

The gear case 110 houses a gear assembly configured to drive the dynamicworking tool such as a grinding disc. Referring to FIGS. 2A and 2B, thegear case 110 of the handheld tool 10 includes an upper cover section202 and a lower cover section 205. The lower cover section 205 includesa tool collar or neck 210 secured to the upper cover section via a coverflange 212. The neck 210 may define a cylinder having a central channelthrough which a tool spindle 215 extends. The tool spindle 215, incommunication with the armature assembly housed within the field case115 (via the gear assembly), is rotated by the armature assembly aboutthe spindle rotational axis R. The working tool, e.g., a grinder wheel,is coupled to the tool spindle 215 (seen in FIG. 15B). Consequently,rotation of the spindle 215 causes a corresponding rotation in theworking tool. An exemplary handheld power tool device 10 usable with theshield assembly of the present invention is disclosed in U.S. PatentApplication Publication No. 2008/0146126 to Gallagher et al., thedisclosure of which is incorporated herein by reference in its entirety.

As noted above, the neck 210 of the lower cover section 205 may be agenerally annular cylinder. The neck 210 includes an annular track orgroove 220 extending about the neck circumference. The track 220 may bedisposed at an intermediate neck location (e.g., the track 220 isgenerally horizontal, and is positioned centrally along the height ofthe neck), and slidingly receives guide elements disposed on thecoupling member. One or more axial (vertical) notches 225 are spaced atpredetermined radial locations along the neck 210. The axial notches 225are aligned to receive guide elements extending from the interiorchannel of the coupling member 405 (discussed in greater detail below).

A lock mechanism cooperates with the shield assembly 125 to secure therotational position of the shield assembly with respect to the neck 210and, consequently, the working tool. As seen best in FIG. 2B, a lock armor pawl 235 is pivotally coupled to the flange 212 of the lower coversection 205 (via a fastener 240) such that it pivots about a pivot axisP. As shown, the pawl pivot axis P is generally parallel to the spindlerotation axis R. The pawl 235 is biased into its normal, locked positionvia a biasing member 245 (e.g., a spring) disposed on a spring seat 250mounted on the lower cover section 205 of the gear case 110.

Referring to FIGS. 3A and 3B, the pawl 235 is a lever including anelongated body 305 with a proximal portion 307 including a socket 310whose axis defines the pivot axis P of the lever. The body 305 includesa forward side 315A, an upper side 315B, a lower side 315C, and a rearside 315D. A first or upper boss 320 (also called a lock or pawlprojection) is disposed at an intermediate longitudinal location alongthe body 305, extending from the body forward side 315A. In addition, asecond or lower boss 325 (also called a lock or pawl ramp) extends fromthe body lower side 315C. The lower boss 325, while alignedlongitudinally with the upper boss 320 along the lever body 305, isoffset from the upper boss in the body transverse dimension.Accordingly, the upper boss 320 is positioned forward of the lower boss325 (in the forward pivot direction, i.e., in the pivot direction towardthe spindle 215). The upper boss 320 may be a generally rectangularprotrusion having a tapered surfaces 322A, 322B defining a generallyflat forward edge E1. The lower boss 325 may be generally pyramidal,having ramped surfaces 327A, 327B defining a pointed forward edge E2. Itshould be understood that the dimensions and shape of any of the pawland pawl protrusions may by any suitable for their described purposes.

The pawl 235 further includes a cut-out area 330 on rear body side 315Ddisposed proximate pawl distal end 337. Within the cut-out area 330 is athird or rearward boss 335 (also called a stop member) extends rearwardfrom the rear side 315D of the lever body 305. The third boss 335, whichmay be generally polygonal, is configured to engage the biasing member245 extending from the spring stop 250 on the gear case cover 205. Thebiasing member 245, which is connected to the third boss 335, isconfigured to drive the pawl 235 forward (toward the spindle 215) suchthat the pawl (and specifically the first boss 320 and the second boss325) is biased into engagement with the shield assembly 125 to lock theshield assembly in position (explained in greater detail below).

The shield assembly 125 is configured such that it may be rotatablyadjustable about the working tool in a “hands free” manner duringoperation of the device 10. By “hands free,” it is meant that the shieldassembly 125 may be repositioned along the neck 210 without the use ofauxiliary tools such as wrenches, screwdrivers, etc. Additionally,“hands free” is intended to mean that a user can manipulate the shieldassembly 125 safely while the tool device 10 is in operation withoutengaging the assembly with the user's hands. It should be furtherunderstood that “hands free” does not exclude manual manipulation byhand while the tool device 10 is turned off (e.g., engaging the actuatorby hand to reposition the shield assembly 125).

Referring to FIG. 4, the shield assembly 125 includes a guard orenclosure member 400, a ratchet actuator or bumper member 402, and acoupling member or collar 405. The guard member 400 at least partiallycovers the working tool, typically spanning a limited expanse of theworking tool. By way of specific example, the guard member 400 extendsapproximately 180° around the working tool (e.g., a circular disc).

Referring to FIGS. 5A and 5B, the guard member 400 includes a guard body505 with a base portion 510A, an angled wall portion 510B joined to thebase portion along a first or upper beveled area 515A, and a transversewall portion 510C joined to the angled wall portion along a second orintermediate beveled area 515B. The guard body 505 may further include alip or rim 520 joined to the transverse wall portion 515C along a thirdor lower beveled area 515C. The base portion 510 is generally planar,and is oriented generally orthogonal to the spindle axis. The transversewall portion 510C is oriented generally transverse (e.g., generallyorthogonal) to the base portion 510A. As shown, the guard body 505 isgenerally semicircular, defining a first end 522A and a second end 522B.

A guard flange 530 extends upward from the base portion 510A of theguard body 505, being disposed about the inner perimeter of a bodycut-out area 532. The guard flange 530 defines a generally arcuate wallincluding a plurality of angularly-spaced windows 535 disposed proximatewall upper (distal) edge 537. The guard flange 530 further includes aplurality of radially-extending guide elements or spring tabs 540angularly spaced at predetermined locations about the flange interiorsurface 542. The guide elements 540 are sized and positioned to alignwith the notches 225 formed into the neck 210 on the gear case cover205, as well as to be received by and ride along the track 220 formedinto the neck 210.

The actuator 402 is configured to selectively disengage the lockmechanism when the actuator is moved relative to the guard member 400and/or the coupling member 405. Referring to FIGS. 6A and 6B, theactuator 402 includes a body 605 and a collar 610. The body 605,generally contoured to the body 505 of the guard member 400, includes abase portion 615A and an angled or ramped portion 615B. The actuatorbody 605 further includes one or more apertures 620 formed into the bodyand one or more rib elements 622 disposed at predetermined locationsalong the body and extending from body upper surface. Rib elements 622may also be contacted to urge the actuator.

The actuator 402 may further include protruding elements or engagementfingers depending from the actuator body 605 (also called peripheralextensions). In the embodiment illustrated, the actuator 402 includes afirst finger 625A and a second finger 625B angularly spaced along theactuator body 605. For example, the first finger 625A may bediametrically opposed from the second finger 625B (i.e., the fingers maybe approximately 180° apart) such that each fingers is proximate guardbody end 522A, 522B. Each finger 625A, 625B extends downward (axially)from the angled wall section 615B of the actuator body 605. Each finger625A, 625B may be generally L-shaped, including a radially-extending armportion 630A, 630B and an axially-extending projection portion 635A,635B.

The fingers 625A, 625B extend radially outward from the actuator body605 such that the rear edge 645A of each finger 625A, 625B is offsetfrom the rear edge 645B of the body 605 by offset distance d. Statedanother way, the fingers 625A, 625B are configured to extend beyond theperimeter/periphery of the guard member 400. With this configuration,the fingers 625A, 625B define contact areas that are engaged to move theactuator 402 relative to the guard member 400. The clearance provided bythe fingers 625A, 625B create a predetermined travel distance (distanced) the actuator 402 travels before it becomes flush with the body 505 ofthe guard member 400 (offset seen best in FIGS. 10B and 10C).

The actuator collar 610 is generally annular, defining an opening 640that receives the neck 210 of the gear case cover 205. A generallyannular collar flange 655 is disposed on the actuator collar 610,extending from collar top surface 660. The collar flange 655 isgenerally coaxial with the ratchet collar 610, possessing an innerdiameter that is coextensive with the ratchet collar and an outerdiameter that is smaller than the outer diameter of the collar. Thecollar flange 655 includes a plurality of engagement notches or members670 angularly spaced about the flange, each engagement notch beingconfigured to receive the lower boss 325 of the pawl 235. By way ofexample, each engagement notch 670 is generally V-shaped, extendingradially inward from the outer circumference 672 of the flange 655 anddefined by a first ramped or angled surface and a second ramped orangled surface.

In an embodiment, the collar flange 655 has a first or forward set 675Aof engagement notches and a second or rearward set 675B of engagementnotches. The first notch set 675A includes a plurality of V-shapedengagement notches 670 angularly spaced along the forward portion of thecollar flange 655. The second notch set 675B of includes a singleV-shaped engagement notch 670 disposed along the rearward portion of theflange. By way of specific example and as shown in FIG. 6B, the firstnotch set 675A includes a plurality of notches positioned forward of afirst line L1 that bisects the actuator collar 610 in a first direction.The forward set 675A includes a first forward notch 670′ generallyaligned with a second line L2 bisecting the actuator collar 610 in asecond direction that is generally orthogonal to the first linedirection. The remaining notches of the forward set 675A extendingapproximately 45° on either side of the first forward notch 670′ (and,as such, the second line L2). The rearward notch set 675B, in contrast,includes a single notch 670″, the single notch being diametricallyopposed to the first forward notch 670′ of the forward notch set 670A(i.e., the single rearward notch 670″ is also generally aligned withsecond line L2). It should be understood that each notch set 670A, 670Bmay include any number of notches suitable for its described purpose.The dimensions and shape of the notches, moreover, may be any suitablefor their described purpose.

The actuator 402 further includes a female connector portion configuredto mate with a male connector portion on the coupling member 405.Referring to FIGS. 6C and 6D, the interior surface of the actuatorchannel 640 includes a cavity 680 defined by a first or lower recess 682formed into the actuator collar 610 and a second or upper recess 684formed into the collar flange 655. As illustrated, lower recess 682includes dimensions greater than those of the upper recess 684, with thelower recess being wider than the upper recess. The lower recess 682 isdefined by a first lateral side 686A, a second lateral side 686B, afirst shoulder portion 688A, and a second shoulder portion 688B.Similarly, the second recess 684 includes a first lateral side 690A, asecond lateral side 690B, and a shoulder portion 692. With thisconfiguration, the cavity 680 is configured to receive tab elements onthe coupling member, permitting limited rotational movement of thecoupling member within the actuator channel 640 (discussed in greaterdetail below).

The coupling member 405 couples the guard member 400 and the actuator402 to the neck 210. Referring to FIGS. 7A and 7B, the coupling member405 includes a generally annular body 705 defining a central opening 707and having a lower portion 710, an upper portion 715, and a channel orrace 720 extending along the circumference of the body and orientedbetween the upper and lower portions. As noted above, the couplingmember 405 includes a male connector portion that is received by thefemale connection on the actuator 402. Specifically, the lower bodyportion 710 includes a radially-extending platform or shelf 725 disposedwithin the rear semicircle of the body 705 (i.e., behind a first lineLL1 bisecting the coupling member in a first direction, as shown in FIG.7B). The platform 725 may extend approximately 45° about the perimeterof the body 705. The platform 725 includes a first boss or tab 730Adisposed in spaced relation from a second boss or tab 730B. By way ofexample, the tabs protrude upward from platform upper surface 732, witheach tab 730A, 730B being positioned generally equidistantly from asecond line LL2 bisecting the coupling member in a second directiongenerally orthogonal to the first direction.

The upper body portion 715 includes one or more windows 735 configuredto receive the upper boss 320 of the pawl 235 coupled to the flange 212of the gear case cover 205. In an embodiment, the coupling member 405includes a set of forward windows 735A and a set of rearward windows735B. The forward window set 735A includes a plurality of windows 735angularly spaced along the forward section of the coupling member body705 (i.e., generally within the forward semicircle defined by line LL1).The rearward window set 735B includes a single window 735 centrallydisposed along the rearward section of the coupling member body 705(i.e., within the rearward semicircle defined by the first line LL1).The first forward window 735′ of the forward window set 735A may bealigned with the single rear window 735″ of the rear window set 735Balong the second line LL2. It should be understood that each window set735A, 735B may include any number of windows suitable for its describedpurpose. The dimensions and shape of the windows, moreover, may be anysuitable for their described purpose.

Each window 735 of the forward window set 735A generally aligns with acorresponding window 535 on the guard flange 530 of the guard member 405(the position of the guard member is generally fixed with respect to thecoupling member, with the coupling member and the moving in concert).Consequently, when the windows 535, 735 are aligned, the upper boss 320of the pawl 235 passes through each of the guard member 400 and thecoupling member 405. Furthermore, upper boss 320 extending into window735B is the position in which the assembly 125 can be removed from thegrinder neck 210.

In addition, the window sets 735A, 735B of the coupling member 405 alignwith the forward 670A and rearward 670B notch sets of the collar flange655. That is, each window 735 of the coupling member 405 aligns with acorresponding engagement notch 670 on the flange 655 of the actuator402. With this configuration, the pawl 235 is able to simultaneouslyengage a notch 670 (via the lower boss 325) and a window 535, 735 (viathe upper boss 320) when the coupling member 405 and the actuator 402are oriented in their normal positions such that the notches and thewindows are in alignment.

As noted above, the coupling member 405 couples to the actuator 402. Toconnect the coupling member 405 to the actuator 402, the body 705 of thecoupling member 405 is inserted into the actuator channel 640 such thatthe platform 725 and tab elements 730A, 730B are positioned within thelower recess 682 of the collar cavity 680, with the first tab element730A engaging the first shoulder 688A of the lower recess 682 and thesecond tab element 730B engaging the second shoulder 688B of the lowerrecess 682 (i.e., the tab elements are positioned on opposite sides ofthe upper notch 684 when the coupling member 405 is in its normalposition). With this configuration, the actuator 402 may rotate relativeto the coupling member 405 (and vice versa), the rotation being limitedby stops created by the tabs engaging the sides 685A, 686B of the lowerrecess 682.

The shield assembly 125 further includes an alignment system operable toorient the actuator 402 into a predetermined, normal position relativeto coupling member 405 thereby consistently aligning the notches 670 ofthe actuator with the windows 735 of the coupling member. In theembodiment shown in FIG. 8A, the alignment feature 800 includes abiasing member 805 disposed within the cavity 680 of the actuator 402.The biasing member 805, which spans the first 682 and second 684recesses, is positioned between the first tab element 730A and secondtab element 730B of the coupling member 405. With this configuration,the biasing member 805 cooperates with the tab elements 730A, 730B toparticularly align the coupling member 405 with respect to the ratchetactuator 402, orienting the components in a normal position relative toeach other. Specifically, when the actuator 402 is in its normalposition, the biasing member 805 (e.g., a spring such as a coil spring)is in its normal, expanded configuration. When the actuator 402 isrotated relative to the coupling member 405 in either direction asindicated by arrow A (e.g., by the user contacting the actuator 402against a work surface), the biasing member 805 becomes compressed asillustrated in FIG. 8B. Once the applied rotational force isdiscontinued, however, the biasing member 805 expands, returning thecoupling member 405 and the actuator 402 back to their respective normalpositions in which the notches 670 and the windows 735 align.

With this configuration, the alignment system drives the actuator 402back to its normal position such that it is particularly aligned withthe coupling member 405. This alignment system ensures that when thebiasing member 805 is in its normal, expanded configuration (i.e., whenactuator 402 is not being rotated relative to the guard member 400), theactuator 402 has a particular relative orientation with respect to thecoupling member 405. When particularly aligned, the windows 735 of thecoupling member 405 are aligned with the notches 670 of the actuatorflange 655, enabling the pawl 235 to lock the guard member 400 in adesired relative position with respect to the cutting tool (discussed ingreater detail below). Should the ratchet actuator 402 be rotatedrelative to the coupling member 405 by application of a force sufficientto overcome the biasing force of the biasing member 805, the windows andnotches will become temporarily misaligned, but will realign uponremoval of the outside force.

Another embodiment of the alignment system is illustrated in FIG. 9A. Asshown, the first tab element 730A of the coupling member 405 is biasedvia a first biasing member 905A extending from the first lateral side690A of the upper recess 684 to a lateral side 910A of the first tabelement. Similarly, the second tab element 730B is biased via a secondbiasing member 905B extending from the second lateral side 690B of theupper recess 684 to a lateral side 915B of the second tab element. Withthis configuration, the biasing members 905A, 905B cooperate toparticularly align the coupling member 405 with respect to the actuator402, orienting the components in a normal position relative to eachother. Specifically, when actuator 402 is rotated relative to thecoupling member 405 in either direction (or vice versa, as indicated byarrows), one of the biasing members 905A, 905B is compressed while theother biasing member 905, 905B is extended. Upon removal of thecontact/rotational force, the biasing members 905A, 905B drive thecomponents back to their normal relative position.

FIG. 9B illustrates another configuration of the alignment system. Asshown, instead of having two tab elements 730A, 730B, the couplingmember 405 has a single tab 920, with each lateral side of the singletab element 930A, 930B being coupled to a biasing member 935A, 935B.Again, the biasing members 930A, 930B cooperate to position the actuator402 in a predetermined rotational position with respect to the couplingmember.

FIG. 9C illustrates still another embodiment of the alignment system.Here, the coupling member 405 does not include a platform 725 or tabelements 730A, 730B, but instead includes a recess 940 that aligns witha cavity 945 on the actuator 402 having dimensions similar to that ofthe coupling member recess 940 to define a pocket 950. A single biasingmember 950 is disposed within the pocket 955 defined by the recesses680, 940. The biasing member 950 biases the components in a mannersimilar to that described above.

With the above described configuration, the actuator 402 is coupled tothe coupling member 405 such that the actuator is permitted to rotateabout the coupling member to a limited extent. The actuator 402 isfurther coupled to the guard member 400 (e.g., via snap fit). The guardmember 400, in turn, is coupled (e.g., captured) to the neck 210 of thegear case cover 205 via the guard member flange 530. When coupled, theguide elements 540 on the guard member flange 530 are slidably receivedby the track 220 formed into the neck 210. As a result, the guideelements 540 travel along the track 220, guiding the rotation of theguard member 400 along the neck 210. In addition, the guide elements 540may also function as biasing members, biasing the guard member 400radially outward from the spindle 215 to maintain frictionallyengagement between the flange 530 of the guard member 400 and thecoupling member 405.

The operation of the device is explained with reference to FIGS.10A-10E. In its normal (initial) position (FIG. 10A), the forward windowset 735A of the coupling member 405 is aligned with a correspondingwindow 535 on the guard flange 530. Additionally, each notch 670 of theforward notch set 675A on the collar flange 655 is generally alignedwith the windows 735 of the forward window set 735A. Similarly, thesingle rearward window 735″ on the coupling member 405 is aligned withthe single rearward notch 670″ on the actuator flange 655. The pawl 235,moreover, is disposed in its normal, locked position. In the pawl lockedposition, the upper boss 320 passes through the rearward coupling memberwindow 735″ and the lower boss 325 engages the rearward actuator notch670″. In this locked configuration, the shield assembly 125 is secured,i.e., the rotational position of the guard member 400, the actuator 402,and the coupling member 405 are fixed via interlocking with pawl 235.

To place the pawl 235 in its unlocked position, the user contacts andurges or bumps the actuator 402 against a surface. Specifically, theuser contacts the rear edge 645A of one of the fingers 625A, 625Bagainst a surface (or engages manually, e.g., by pressing with a hand).Once the force applied (indicated by arrow F) is sufficient to overcomethe biasing force placed on the pawl 235 by the pawl biasing member 245,as well as the biasing force of the alignment system biasing member 805,the actuator 402 begins to rotate (indicated by arrow S in FIG. 10B).The rotation of the actuator continues 402 may continue until the fingerrear edge 645A becomes flush with the rear edge 645B of the guard memberbody 505. As the actuator 402 rotates, the ramped surfaces of the notch670 drive the pawl 235 outward, away from the spindle 215. That is, thelower boss 325 is driven away from the coupling member 405 and out ofits notch, which, in turn, pivots the pawl 235 outward at a distancesufficient to move the upper boss 320 out of engagement with therearward coupling member window 735″. FIGS. 10D and E show crosssections of pawl 235 in the locked and unlocked positions respectfully.

When the upper boss 320 has cleared the rearward coupling member window735″, the shield assembly 125 (the guard member 400, the ratchetactuator 402, and the coupling member 405) may be rotated about the neck210 of the gear case cover 205 until the desired shield assemblyposition is reached (FIG. 10C). That is, continuing to contact theshield assembly 125 against the work surface will rotate the shieldassembly 125 about the neck 210 to the next window opening 735. Once thedesired rotational position is achieved, the lock mechanism may remainin its locked position. That is, the shield assembly 125 may be rotateduntil the bosses 320, 325 of the pawl 235 are aligned with a desiredwindow 735 and its associated notch 670. Once the lower boss 325 isaligned with the desired notch 670, the operator discontinues contactingthe guard member 400 and the actuator 402 against the work surface. As aresult, the pawl 235 is driven inward (toward the spindle 215) by thepawl biasing member 245, positioning the lower boss 325 within thedesired notch 670 and positioning the upper boss 320 within theassociated window 735. The pawl 235 is now in its locked position,securing the rotational position of the shield assembly 125 with respectto the neck 210.

If, for any reason, the windows of the coupling member 405 and thenotches 670 on the flange 655 of the actuator 402 become misalignedduring rotation of the shield assembly 125, the alignment system 800will automatically reorient the coupling member 405 and with respect tothe actuator 402 (and vice versa) to rotationally align the components.As mentioned above, in order for the pawl 235 to engage the notch 670and its associated window 735, it is necessary that the notch and windowbe aligned. Thus, should the notch 670 and window 735 become misaligned,the biasing member 805 will act on the tab elements 730A, 730B asdescribed above to drive the rotational position of the components intotheir normal, predetermined position, in which the notches 670 and thewindows 735 align.

Another embodiment of a hands-free, selectively repositionable shieldassembly is illustrated in FIGS. 11A-11D. As shown, the shield assembly1100 includes a guard member 1105 having a generally semicircular body1107 defining a first lateral end 1110A and a second lateral end 1110B.The body 1107 of the guard member 1105 includes a neck or flange portion1115A, a generally planar base portion 1115B and a transverse wallportion 1115C. The shield assembly 1100 further includes a generallyannular guard collar 1120 configured to surround the neck 1125 of thegear case cover 1130. The guard collar 1120 includes a generallyrectangular window 1135 and a post or tab 1140 extending radiallyoutward from the guard collar, along the window lower edge.

The neck 1125 of the gear case cover 1130 defines a round gear,including a plurality of gear teeth 1145 that cooperates with a pawl onthe shield assembly 1100 to provide incremental rotational adjustment ofthe guard member with respect to the spindle and/or working tool(discussed in greater detail below). In an embodiment, the gear teeth1145 are sloped in a single direction and are uniformly spaced along thecircumference neck 1125. Each gear tooth 1145, moreover, may beasymmetrical, with each tooth having a moderate slope along one edge anda steeper slope on the other edge.

A sliding actuator 1150 is disposed along an end 1110A, 1110B of theguard member 1105. The sliding actuator 1150 defines a generallyS-shaped bracket including a proximal short arm section 1152A coupled tothe guard member flange portion 1115A, a long arm section 1152Bextending radially from the proximal short arm section 1152A, and adistal short arm section 1152C extending axially along the transversewall portion 1115C. The distal short arm section 1152C includes a tab1155 extending radially outward therefrom. The long arm section 1152Bincludes a one or more elongated guide slots 1160A, 1160B that eachmoves along a corresponding guide post 1162A, 1162B. A biasing membersuch as a spring 1151 biases the sliding actuator 1150 in a normalposition relative to the guard member 1105. With this configuration, thesliding actuator 1150 moves (e.g., translates) along the guard member1105 from an extended position (illustrated), in which it protrudesbeyond the end 1110A, 1110B of the guard member 1105, to a retractedposition, in which the outer edge of the actuator 1150 is generallyflush with respect to guard body end 1110A, 1110B.

The sliding actuator 1150 is in communication (e.g., is mechanicallylinked) with a lock mechanism configured to selectively secure the guardmember 1105 in a desired rotational position along the collar (and thuswith respect to the working tool). Referring to FIGS. 11C and 11D, thelock assembly includes a linkage or rod 1165 pivotally coupled to theproximal section 1152A of the actuator 1150 along the linkage proximalend. In addition, the linkage distal end is pivotally coupled to a pawl1170, which, in turn, is pivotably coupled to the window tab 1140. Thepawl 1170 selectively engages the gear teeth 1145 on the neck 1125 ofthe gear case 1130 to prevent the rotation of the gear in apredetermined direction (e.g., in a clockwise and/or a counterclockwisedirection).

In operation, the shield assembly 1100 begins in its normal, lockedposition, in which the actuator 1150 is in its extended position, beingbiased by biasing member. In the locked position, the rotation of theguard member 1105 with respect to the neck 1125 (and thus the workingtool) is prevented. To release the shield assembly 1100, the operatorcontacts the tab 1155 of the actuator 1150 against an object such as theworkpiece or work surface. Otherwise, the operator may manually engagethe actuator 1150 by grasping the tab 1155. Engaging the actuator 1150moves the actuator from its extended position to its retracted position.As the actuator 1150 moves, the linkage member 1165 is driven outward,pivoting the pawl 1170 outward, away from the neck 1125. The pawl 1170disengages the gear teeth 1145 of the neck 1125. In this disengagedposition, the shield assembly 1100 may be rotated about the neck 1125 toreposition the guard member 1105 with respect to the working tool. Whenreleased, the actuator is driven back to its normal position by biasingmember, returning the pawl 1170 into engagement with the gear teeth1145. With this configuration, the operator may simply contact an edgeof the guard member against a stationary object such as a workpiece toincrementally rotate the shield assembly 1100 about the neck 1125.

Another embodiment of the selectively repositionable shield assembly isillustrated in FIGS. 12A-12C. The shield assembly 1200 includes a guardmember 1205 including a generally semicircular body 1107 defining afirst end 1210A and a second end 1210B, and including a generally planarbase portion 1215A and a transverse wall portion 1215B. The guard member1205 further includes an annular collar 1220 operable to secure theshield assembly 1200 to the neck 1225 of the gear case cover 1230. Theneck 1225 includes a plurality of axial notch surfaces 1232 disposed atselected locations along the collar perimeter.

A first sliding actuator 1235A is disposed along the first transverseend 1210A of the guard member 1205 and a second sliding actuator 1235Bis disposed along the second transverse end 1210B of the guard member.The sliding actuator 1235A, 1235B defines a generally L-shaped structureincluding a long arm section 1240A and a distal short arm section 1240Bdisposed over the transverse wall portion 1215B of the guard 1205. Thedistal short arm section 1240B includes a tab 1255 extending radiallyoutward therefrom. With this configuration, the each actuator 1235A,1235B slides along the guard 1205 from an extended position, in which itprotrudes beyond its respective guard body end 1210A, 1210B, to aretracted position, in which the actuator is generally flush withrespect to guard body end.

A generally oblong outer collar 1260 surrounds the neck 1225. With thisconfiguration, the outer collar defines an outer race and the neck 1225defines an inner race. A first sprag 1265A, disposed along first collarend 1267A, is pivotally coupled to the outer collar 1260. Similarly asecond sprag 1265B, disposed along the second collar end 1267B oppositethe first collar end, is pivotally coupled to the outer collar 1260. Byway of example, the first sprag 1265A may be diametrically opposed tothe second sprag 1265B with respect to the neck 1225 (i.e., the firstsprag is angularly spaced from the second pawl by approximately 180°).Each sprag 1265A, 1265B possesses an hour-glass or figure-eightstructure. Each sprag 1265A, 1265 is configured to rotate from a firstposition, in which it engages a flange notch surface 1232 to a secondposition, in which it is disengaged from the notch surface. In addition,each sprag 1265A, 1265B is in communication (e.g., mechanically linked)to an associated actuator 1235A, 1235B. Specifically, the first actuator1235A is connected to the first sprag 1265A via a first rod 1270A thatforms the actuator. The first rod 1270A is coupled to the first sprag1265A proximate the sprag central pivot point. Similarly, the secondsprag 1265B is connected to the second actuator 1235B via a second rod1270B, proximate the central pivot point of the second sprag. With thisconfiguration, engaging an actuator 1235A, 1235B causes the actuator torotate the sprag from its normal, engaged position to its disengagedposition. Each actuator 1235A, 1235B is biased via a biasing member(e.g., a spring) such that once the actuator is disengaged, it returnsto its normal (engaged) position.

The sprags 1265A, 1265B are arranged so that, in their normal position,the first sprag 1265A prevents rotation of the guard member 1205 in afirst direction (e.g., a clockwise direction), while permitting rotationof the guard member in a second (opposite) direction (e.g., acounterclockwise direction). Similarly, the second sprag 1265B, in itsnormal position, prevents rotation of the guard member 1205 in thesecond direction, but permits rotation of the guard member in the firstdirection. In operation, to rotate the guard member 1205 in the firstdirection, a user bumps the first actuator 1235A against a surface suchas the workpiece, causing the actuator to move along the guard member.The actuator 1235A, in turn (via rod 1270A), rotates the first sprag1265A from its engaged to its disengaged position. Since the secondsprag 1265B is already configured to allow the guard member 1205 torotate in the first direction, the operator may now rotate the guardmember in the first direction by continuing the application of force tothe guard member 1205 via contact. Alternatively, to rotate the guardmember 1205 in the second direction, the operator bumps the secondactuator 1235B against an object (e.g., the work surface) to rotate thesecond sprag 1265B from its engaged position to its disengaged position.Since the first sprag 1265A is already configured to allow the guardmember 1205 to rotate in the second direction, the operator may nowrotate the guard in the second direction.

Another selectively repositionable shield assembly in illustrated inFIGS. 13A-13D. As shown, the shield assembly 1300 includes a guardmember 1305 including a generally semicircular body 1307 defining afirst end 1310A and a second end 1310B. The guard member 1305 includes agenerally planar base portion 1315A oriented generally orthogonal to therotational axis of the spindle 215 and a transverse portion 1315Boriented generally parallel to the rotational axis of the spindle. Agenerally annular guard collar 1320, extending upward from the guardmember body 1307, includes a plurality of windows angularly spaced aboutthe collar. By way of specific example, the guard collar 1320 mayinclude a single rear window 1325A (disposed centrally along the rearsemicircle defined by the collar) and a plurality of forward windows1325B (disposed along the forward semicircle of defined by the collar).

As seen best in FIG. 13B, the guard collar 1320 further includes one ormore guide tabs 1330A, 1330B angularly spaced along the interior surface1335 of the collar (e.g., disposed proximate the lower edge of thecollar). The guide tabs 1330A, 1330B are received in and travel along anaxial notch 1337 formed into the neck 1339 of the gear case cover 1340.The guide tabs 1330A, 1330B, moreover, move along a track 1342 formedinto the circumference of the neck 1339.

In addition, the guard collar 1320 includes one or more guard springs1345A, 1345B angularly spaced along guard collar interior surface 1335.In an embodiment, the guard springs 1345A, 1345B are generallyvertically aligned with each guide tab 1330A, 1330B, each being spacedlaterally from a corresponding side of the rear guard collar windows1325B. The guard springs 1345A, 1345B are configured to remove clearancebetween the guard collar 1320 and the neck 1339 of the gear case cover1340.

Referring to FIG. 13C, a stop lever 1350 is pivotably coupled to gearcase cover 1340 via a fastener 1355. The stop lever 1355 is biased intoengagement with the guard collar 1320 via a biasing member 1360 such asa spring. The stop lever is generally L-shaped, in including anengagement portion 1365A and a distal arm portion 1365B. The engagementportion 1365A is configured to pass through the windows 1325A, 1325B onthe guard collar 1320; moreover, the end 1370 of the engagement portion1365A is asymmetrically tapered, with an angled or ramped surface 1375Aand a straight surface 1375B. With this configuration, when theengagement portion end 1370 is positioned within a collar window 1325A,1325B, rotation of the collar is permitted in the direction of theangled surface 1375A, but is prevented in the direction of the straightsurface 1375B.

In operation, the biasing member 1360 (e.g., a torsion spring) biasesthe stop lever 1350 (and, in particular, the engagement portion 1365A)into contact with the guard collar 1320. In this normal, engaged orlocked position, the engagement portion 1365A is positioned within acollar window 1325A, 1325B, securing the rotational position of theguard collar 1320 (and thus the shield assembly 1300) relative to theworking tool (e.g., a grinder disc). To reposition the guard member 1305(i.e., to adjust the rotational position of the shield assembly 1300with respect to the working tool), the user contacts the guard body end1310A, 1310B against a surface to rotate the guard member in thedirection of the stop lever angled surface 1375A with a force sufficientto overcome the biasing force of the biasing member. This, in turn,causes the guard collar 1320 to rotate about the neck 1339 of the gearcase 1340 in the direction of the angled surface 1375A, with the guidetabs 1330A, 1330B sliding along track 1342. As the guard collar 1320rotates, the engagement portion 1365A of the stop lever 1350 is drivenradially outward, i.e., it is pivoted away from the guard collar. Thecollar continues to rotate until the engagement portion 1365A is alignedwith the desired window 1325A, 1325B. Once aligned, the stop leverengages the neck 1339, returning the lock mechanism to its normal,engaged or locked position in which the shield assembly 1300 is securedin position. With this configuration, each window serves as a detentposition, permitting a user to adjust the rotational position of theshield assembly 1300 along the neck 1339 in discrete increments.

Another repositionable shield assembly in illustrated in FIG. 14. Asshown, the shield assembly 1400 includes a guard member 1405 including agenerally semicircular body 1407 defining a first end 1410A and a secondend 1410B, as well as a generally planar base portion 1415A and a wallportion 1415B oriented transverse (generally orthogonal) to the baseportion. The guard member 1405 further includes a generally guard collarlock mechanism 1420 operable to selective engage the neck 1425 of thegear case cover. The lock mechanism includes a bracket 1435 incommunication with a first actuator 1440A disposed along the first guardbody end 1410A and a second actuator 1440B disposed along second guardbody end 1410B. In an embodiment, the first actuator 1440A is a leverpivotally coupled to the guard body 1407 at first pivot point 1445A.Similarly, the second actuator 1440B is a lever pivotally coupled toguard body 1407 at a second pivot point 1445B. The inner portion of theactuator 1440A, 1440B (i.e., the portion closes to the neck 1420)includes a protruding member or cam 1450A, 1450B that, when pivoted,alters the diameter of the bracket member 1435 to increase or decreasethe clamping force exerted by the bracket on the neck 1425.

The bracket 1435 includes a first loaded fastener 1455A in communicationwith the first actuator 1440A and a second loaded fastener 1455B incommunication with the second actuator 1440B. Each loaded fastener1455A, 1455B includes a fastener 1457 (e.g., a bolt) couples a first orlarge bracket portion 1460 to a second or small bracket portion 1465separable from the large bracket portion. A biasing member 1470 (e.g., aspring), positioned between the small bracket portion and a washer 1472mounted on the shaft of the fastener, biases the bracket portions 1460,1465 toward each other. As a result, in its normal position, the bracket1435 is generally closed, applying clamping pressure sufficient tosecure the rotational position of the shield assembly 1400 viafrictional force.

In operation, engaging an actuator 1440A, 1440B (indicated by arrow F)pivots the actuator such that the cam 1450A, 1450B engages the washer1472, overcoming the biasing force of the biasing member 1470 anddriving the washer upward along the shaft of the fastener 1477 (towardthe head of the fastener 1457). Movement of the washer 1472 compressesthe biasing member 1470, thereby decreasing the clamping force appliedby the bracket 1435. That is, compressing a biasing member 1470separates the large bracket 1460 portion from the small bracket portion1465. Once the clamping pressure is reduced, the shield assembly 1400may be rotated about the neck 1425 to its desired rotational position.Releasing the actuator 1440A, 1440B permits the biasing member 1470 toexpand, driving the actuator to its normal position and drawing thebracket portions 1460, 1465 together to increase the clamping pressure.

In another aspect of the invention, operator visibility of the workingtool (e.g., a circular grinder) through the guard is provided, while theshielding ability of the guard is maintained. Referring to FIGS.15A-15C, the shield assembly 1500 includes a guard member 1505 similarto that described above, including a generally semicircular body 1507having a first end 1510A and a second end 1510B. The guard member 1505,configured to partially enclose the working tool 1512 (e.g., a grinderblade), includes a base portion 1515A and a transverse wall portion1515B (e.g., transverse wall portion is oriented generally orthogonal tothe base portion 1515B), as well as bevel portions 1517A, 1517B, similarto those described above. By way of example, the dimensions of the guardmember 1405 are selected such that the guard covers approximately 180°of the grinding tool (a generally circular disc). The guard member 1505further includes a generally annular guard collar 1520 operable tosecure the shield assembly 1500 to the neck of the gear case cover 1530.Specifically, the guard collar 1520 includes a clamp mechanism 1535 thatselective captures the shield assembly 1500 to the neck.

The guard member 1505 is configured to provide a see-through effect thatenables an operator to view the working tool 1512 through the guardmember during tool operation. Specifically, the guard member 1505includes a plurality of apertures 1540 angularly spaced about thetransverse wall portion 1515B at regular intervals. As shown, eachaperture 1540 may be an elongated slot formed into the transverse wallportion 1515B, with each slot extending inboard from the guard membercircumference. Each slot is oriented at an angle that is offset from 90°with respect to the transverse wall portion 1515B and/or thecircumferential edge 1547 of the working tool 1512. In an embodiment,each slot 1540 is angled approximately 45° with respect to thetransverse wall portion 1515B of guard body 1507. As shown, each slot1540 extends into the transverse wall 1515C and beveled edges 1517A,1517B, terminating in a generally rounded slot end 1550.

Another embodiment for a see-through shield assembly is illustrated inFIGS. 16A and 16B. As shown, the shield assembly 1600 includes a guardmember 1605 similar to that described above, including a generallysemicircular body 1607 having a first end 1610A and a second end 1615B,as well as including a neck portion 1615A, a generally planar baseportion 1615B, and a transverse wall portion 1615C (e.g., transversewall portion is oriented generally orthogonal to the base portion1615B), as well as bevel portions 1617A, 1617B. The guard member 1605further includes a generally annular guard collar 1620 operable tosecure the shield assembly 1600 to the neck on the gear case cover 1630.Specifically, the guard collar 1620 includes a clamp mechanism 1635 thatselectively captures the shield assembly 1600 to the tool device. Inthis embodiment, the apertures 1640 are in the form of a series oflouvers including an opening 1645 and a U-shaped tab or tongue member1650 extending angularly inward from the transverse wall portion 1615C.The tongue members 1650 are operable to deflect particulates,maintaining the particulates within the interior of the guard member1605.

Another embodiment of the see-through shield assembly is illustrated inFIGS. 17A and 17B. As shown, the shield assembly 1700 includes a guardmember 1705 similar to that described above, including a generallysemicircular body 1707 having a first end 1710A and a second end 1710B,and including a neck portion 1715A, a generally planar base portion1715B, and a transverse wall portion 1715C, as well as beveled portions1717A, 1717B. The guard member 1705 further includes a generally annularguard collar 1720 operable to secure the shield assembly 1700 to theneck of the gear case cover (not illustrated). Specifically, the guardcollar 1720 includes a clamp mechanism 1735 that selectively capturesthe shield assembly 1700 to the neck.

In this embodiment, the guard member apertures 1740 are in the form ofgenerally rectangular holes or openings. The shield assembly 1700further includes an elongated, generally U-shaped band 1745 adapted tofit within the generally U-shaped interior cavity 1747 defined by thetransverse wall portion 1715C of the guard body 1707. The band 1745includes a plurality of vents 1750 spaced longitudinally along the band.Each vent 1750 includes an opening 1755 and an angled baffle 1760disposed at an angle with respect to the transverse wall portion 1715Cof the guard member 1705. The vents 1750 are configured such that thevent opening 1755 aligns with a corresponding guard aperture 1740 formedinto the transverse wall portion 1715C. The baffles 1760 cover theapertures 1740, deflecting the particulates, thereby maintaining theparticulates within the guard member 1705. The band 1750 may be formedof the same or different material as the guard member 1705, and may bepermanently or temporarily attached the guard member.

Thus, the present invention provides an accessible guard lock thatprovides a peripheral extension of a guard lock so that a user can holdthe tool with both hands and engage/bump the peripheral extension on asurface (e.g., the work piece) to unlock the guard relative to the toolneck. Furthermore, the peripheral projections (the fingers) arepositioned such that a bump of the peripheral projection also urged theguard in a direction of desired guard position. The accessible guardlock described above includes a pawl with two bosses that engage theshield assembly along two points of contact, namely, along the flange ofthe actuator and along the window of the collar. That bosses areeffective radially offset with respect to the spindle. With thisconfiguration, a user can adjust the position of the shield assemblyabout the spindle while the tool device is still in operation.

While the present invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof. Forexample, regarding the repositionable shield assembly, each of the guardmember, actuator, and the coupling ring may possess any suitabledimensions (size and/or shape) suitable for its described purpose. Thedegree of movement provided between the actuator and the coupling memberis not particularly limited. While the repositionable assembly isillustrated without the see-through guard members, it should beunderstood that the see-through guard members may be incorporated in therepositionable shield assembly.

Regarding the see-through guard members, the apertures may be anysuitable dimensions (size and/or shape) suitable for its describedpurpose. The guard members, moreover, may include any number ofapertures disposed along its transverse wall portion. While a simpleclamp is illustrated for clamping the shield assembly to the neck, othercoupling mechanisms may be utilized, including the repositionableconfigurations described above.

Thus, it is intended that the present invention covers the modificationsand variations of this invention provided they come within the scope ofthe appended claims and their equivalents. It is to be understood thatterms such as “top”, “bottom”, “front”, “rear”, “side”, “height”,“length”, “width”, “upper”, “lower”, “interior”, “exterior”, and thelike as may be used herein, merely describe points of reference and donot limit the present invention to any particular orientation orconfiguration.

1-20. (canceled)
 21. A guard lock for a powered apparatus, the poweredapparatus having a neck extending from a gear case, the guard lockcomprising: a guard member, the guard member having a body portion forat least partially surrounding a working member of the power tool and acollar portion connected to and extending from the body portion, thecollar including multiple windows that are spaced from one another, astop lever coupled to the gear case via a fastener about which the stoplever may pivot, the stop lever including an engagement portion and adistant arm portion, the engagement portion including an angled surfaceand a straight surface, the fastener disposed between the engagementportion and the distal arm portion, and a bias member for biasing theengagement portion of the stop lever toward a window of the collarportion, wherein when the engagement portion is positioned within awindow, rotation of the collar is permitted in a direction of the angledsurface but is prevented in a direction of the straight surface, andwherein a depression of the distal arm portion toward the collar pivotsthe engagement portion away from the window.
 22. The guard lock of claim1, wherein the stop lever is L-shaped.
 23. The guard lock of claim 1,wherein the biasing member biases the engagement portion into contactwith the guard collar.
 24. The guard lock of claim 1, wherein the stoplever engages the neck when aligned with a window.
 25. The guard lock ofclaim 1, wherein the collar portion further includes tabs, the neckincludes a track, and the tabs slide along the track as the collarrotates around the neck.